1. Field of the Invention.
This invention relates to urinometers and, more particularly, to such devices for performing a flow rate measurement and automatically printing out a patient record thereof.
2. Description of the Prior Art
In the field of urology, it is often desirable for proper diagnosis and treatment of certain pathological conditions to have a reasonably accurate indication of the rate at which a patient is able to pass urine. One obvious way of determining this measurement, of course, is to have an observer with a stop watch who records the time taken to void a measured amount of urine. One problem with this direct approach, however, is that the administration of this method creates embarrassment or psychological difficulties for many patients to the extent that normal voiding is inhibited. Thus, if the patient voids at all under such conditions, the potentially erroneous data obtained may result in a false diagnosis and a loss of confidence in the results obtained by the physician. Many devices which have been developed in the past for the collection of urine for use in diagnosis of a patient's condition have been less than satisfactory for this reason. A further complication arises from the fact that many of these prior art devices are rather bulky, often difficult to use, and generally expensive by present standards.
Various approaches to solving this problem have relied on the measurement of different parameters related to urine discharge in a manner which does not subject the patient to the normal inhibiting environment, as when the voiding must occur in the presence of medical personnel. Such parameters include the maximum flow rate, the force of expulsion, etc. For example, the capability of a patient to rapidly void a large volume of urine generally indicates an absence of a urethral stricture in the patient. If the force of urine discharge is relatively low in spite of a normal voiding volume per unit time, such a condition suggests inadequate contraction of the patient's bladder, rather than a urethral obstruction. This approach is taken by McWhorter in U.S. Pat. No. 4,200,112 which discloses a device for measuring the force of a urine discharge. As disclosed, the device incorporates a plurality of chambers and tubes to define a urine path and utilizes an indicating strip which changes color when wet in order to provide an indication of the maximum height of the liquid reached in one of the urine compartments. Ciarico in U.S. Pat. No. 3,871,231 discloses a device for measuring the approximate peak flow of urine discharge. Like the device disclosed in the McWhorter patent, this device comprises a plurality of chambers and tubes with an indicator strip that changes color when wet.
Profy in U.S. Pat. No. 3,561,427 discloses a device for measuring the volume of urinary output during a given period of time. This device includes a compartmented drum member which is rotatable about a central axis at a predetermined rate or at periodic intervals, driven by an electric motor and a gear mechanism. The drum member has outer wall portions which are transparent and carry suitable graduations for indicating the volume of urine collected in each compartment, thus enabling the average flow rate to be determined.
German Offenlegungsschrift 2,421,746 discloses urine flow rate measuring equipment comprising a measuring cylinder secured in the top of a graduated flexible bag. Part of the flow is diverted into a drip chamber where it can be collected and its volume measured.
U.S. Pat. No. 4,131,016 of Layton also discloses a peak flow rate measuring device which incorporates a collection bag coupled to a primary receiver in which is removably mounted a graduated standpipe. This device provides a discrete indication as to whether the peak flow rate of urine discharge is above or below a predetermined value, which value may be preselected by adjusting the height of the standpipe within the receiving chamber.
All of the devices referred to thus far are more or less complex in construction and require the fabrication and assembly of a number of separate parts in manufacturing the finished device. Some incorporate moving parts which can get out of order or adjustment and therefore present some difficulty in making reliably repeatable measurements.
One particular flowmeter which has found fairly general acceptance by the medical profession for enabling a measurement of the maximum flow rate of urine discharge is disclosed in the Drake, Jr., U.S. Pat. No. 2,648,981. The device disclosed in this patent comprises a liquid conduit having a plurality of calibrated, vertically spaced orifices amd a compartmented receptacle for collecting liquid which is discharged through the respective orifices. As urine (or any liquid) enters the device, the number of compartments which receive liquid through the respective conduits depends upon the rate of flow, since the urine only reaches the second conduit if the rate of discharge exceeds the permissible flow rate through the first conduit, and only reaches the third conduit if the flow rate exceeds the maximum permissible flow through the first and second conduits, etc.
According to Drake, Jr., medical experience has determined that the normal rate at which a patient voids urine is substantially 20 cc. per second and the disclosed flowmeter is designed to detect deviations from this normal rate. The device is designed to provide measurements which are reasonably accurate for increments of 5 cc. per second, which is sufficient for a satisfactory diagnosis to be made by the physician. Even the Drake, Jr. flowmeter, however, is sufficiently expensive to manufacture that it is the common practice of reuse the device repeatedly, after washing, rather than disposing of the device after a single use. Furthermore, the construction of the device is such that it is difficult to obtain a satisfactory urine specimen from the device. Normally, a specimen is desired for analysis along with the measurement of flow rate which is useful for diagnosis. After the patient has used the Drake, Jr. device, however, he is generally unable to provide a separate specimen by further voiding.
None of the devices disclosed in the patents referenced above possesses the capability of providing a measurement record which is suitable for placing in the patient's file, along with other printout records such as EKG charts, automatic blood pressure and pulse rate recordings, and the like. It would be helpful if there were available a urinometer which is simple to produce, simple to use, low enough in cost to be disposable after use, and capable of automatically generating a permanent patient record for retention in the patient's medical file. The urinometer of the present invention is such a device.